Clusters of COVID-19 associated with Purim celebration in the Jewish community in Marseille, France, March 2020

OBJECTIVES: We investigated possible COVID-19 epidemic clusters and their common sources of exposure that led to a sudden increase in the incidence of COVID-19 in the Jewish community of Marseille between March 15 and March 20, 2020. METHODS: All data were generated as part of routine work at Marseille university hospitals. Biological diagnoses were made by RT-PCR testing. A telephone survey of families in which a laboratory confirmed case was diagnosed was conducted to determine possible exposure events. RESULTS: As of March 30, 2020, 63 patients were linked to 6 epidemic clusters. The 6 clusters were linked to religious and social activities: a ski trip, organized meals for the Purim Jewish celebration in community and family settings on March 10, a religious service and a charity gala. Notably, 40% of the patients were infected by index patients during the presymptomatic period, which was 2.5 days before symptom onset. When considering household members, all 12 patients who tested negative and who did not develop any relevant clinical symptoms compatible with COVID-19 were 1–16 years of age. The clinical attack rate (symptoms compatible with COVID-19, and biologically confirmed by PCR) in adults was 85% compared to 26% in children. CONCLUSIONS: Family and community gatherings for the Purim Jewish celebration probably accelerated the spread of COVID-19 in the Marseille Jewish community, leading to multiple epidemic clusters. This investigation of family clusters suggested that all close contacts of patients with confirmed COVID-19 who were not infected were children.